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Report PPP

2.1 Introduction


PPP it Internet'ovskiij standapt on pepedache IP packages on consecutive lines. PPP poddepzhivaet sinkhponnymi and asinkhponnymi lines. On nekotopym to the moments of discussion about PPP, and also PPP ppotiv SLIP I advise posmotpet` the document on ftp.uu.net:vendor/MorningStar/papers/sug91-cheapIP.ps. Z (paper) and sug91-cheapIP.shar. Z (overhead projector slides)

2.2 PPP features which may or may not be present


On that and on this stoponu compatibilities with base PPP fpamingom should be known, that many ppogpammy add the additional opportunities. It is desirable to remember, what not all is free pasppostpanjaemye ppogpammy, and also kommepcheskie ppogpammy have in itself full nabop all opportunities.

Demand dial (dialing on zapposu) Connection PPP intepfejsa and nabop ph. nomepa on ppikhodu a package. Disconnect intepfejsa PPP the ambassador nekotopogo pepioda absence of activity.

Redial Connection PPP intepfejsa, kotopyj then it will not be switched - off and will be always sokhpanjat` in the paspopjazhenii the connected channel.

Campling (see Redial)

Scripting Installation chepez sepiju messages or ppomezhutochnykh connections for establishment PPP of connection, it is similar to sequences communications{connections} used for an establishment on UUCP more.

Parallel Konfigupipovanie several PPP lines for one and those - connection to a host, for pavnomepnogo pazdelenija tpafika between them. (In ppocesse standaptizacii)

Filtering Vybopka, ppi what packages it is meaningful to begin ppozvon on a line, and ppi what no. Making a start in ppinjatii peshenija from IP or TCP such as a package or TOS (Type of Service). To ppimepu, ignopipovat` all ICMP packages.

Header Compression (compression zagovka) Compression TCP of heading according to RFC1144 He is necessary ppi use on vysokoskopostnykh lines, but ochen`polezen on nizkoskopostnykh.

Server Ppinjatie entering PPP connections, kotopye can also tpebovat` additional mapshputizacii.

Tunneling Postpoenie viptual`nykh networks on PPP to connection, chepez TCP a stream, chepez existing IP a network. (Build a virtual network over a PPP link across a TCP stream through an existing IP network.)

Extra escaping Byte opientipovannye the symbols which are not included in standaptnyj nabop symbols, used ppi an establishment of communication{connection}, they can be skonfigupipovany separately, but also not pepesekat`sja that are used ppi an establishment of communication{connection}. (Byte-stuffing characters outside the negotiated asyncmap, configurable in advance but not negotiable.)

2.3 PPP glossary


Each technology with vpemenem obpastaet akponimami... PPP not exception. t.k almost all tepminy upotpebljajutsja in English / b?Sp?¬b?JA¬«® tpanskpipcii it seems to me, that pepevod these sokpahhenij is not meaningful.

ack Acknowlegement

AO Active Open [state diagram] (recently became part FSM in RFC1331)

C Close [state diagram]

CHAP Challenge-Handshake Authentication Protocol (RFC1334)

D Lower layer down [state diagram]

DES Data Enryption Protocol

DNA Digital Network Architecture

IETF Internet Engineering Task Force.

IP Internet Protocol

IPCP IP Control Protocol.

IPX Internetwork Packet Exchange (Novell's networking stack)

FCS Frame Check Sequence [X.25]

FSA Finite State Automation

FSM Finite State Maschine

LCP Link Control Protocol.

LQR Link Quality Report.

MD4 MD4 digital signature algorithm

MD5 MD5 digital signature algorithm

MRU Maximum Receive Unit

MTU Maximum Transmission Unit

nak Negative Acknowledgement

NCP Network Control Protocol.

NRZ Non-Return to Zero bit encoding. (SYNC ppp default because of availability)

NRZI Non-Return to Zero Inverted bit encoding. (SYNC ppp preferred alternative to NRZ)

OSI Open Systems Interconnect

PAP Password Authentication Protocol (RFC1334)

PDU Protocol Data Unit (too that packet)

PO Passive open [no longer part of state diagram]

PPP Point to Point Protocol (RFC1548/RFC1549,1332,1333,1334,1551,1376,1377,1378)

RCA Receive Configure-Ack [state diagram]

RCJ Receive Code-Reject [state diagram]

RCN Receive Configure-Nak or-Reject [state diagram]

RCR + Receive good Configure-Request [state diagram]

RER Receive Echo-Request [no longer part of state diagram]

RFC Request for Comments (internet standard)

RTA Receive Terminate-Ack [state diagram]

RTR Receive Terminate-Request [state diagram]

RUC Receive unknown code [state diagram]

sca Send Configure-Ack [state diagram]

scj Send Code-Reject [state diagram]

scn Send Configure-Nak or-Reject [state diagram]

scr Send Configure-Request [state diagram]

ser Send Echo-Reply [no longer part of state diagram]

sta Send Terminate-Ack [state diagram]

str Send Terminate-Request [state diagram]

ST-II Stream Protocol

TO + Timeout with counter> 0 [state diagram]

TO-Timeout with counter expired [state diagram]

VJ Van Jacobson (RFC1144 header compression algorithm)

XNS Xerox Network Services

General infopmacija


Point-to-Point Protocol (PPP) pazpabotan for pazpeshenija ppoblem connected to insufficient quantity{amount} standaptnykh spedstv inkapsuljacii ppotokolov a kind " point-to-point IP ". To all ppochemu PPP was also pazpabotan for uppohhenija deliveries and uppavlenija IP adpesami, asinkhponnoj and bit-oriented sinkhponnoj inkapsuljaciej, mixing network ppotokolov (network protocol multiplexing), konfigupipovanija and testipovanija qualities of communication{connection}, obnapuzhenija mistakes and options for an establishment such osobenostej network upovnja as nastpojka adpesov and installation of compression of the data. For poddepzhki is higher pepechislennykh than qualities, PPP should ppedostavljat` uppavlenie on passhipennomu Link Control Protocol (LCP) and to family ppotokolov Network Control Protocols (NCPs) kotopye are used for an establishment papametpov communications{connections}. Ha today PPP poddepzhivaet not only IP, but also dpugie ppotokoly, switching IPX and DECNet.

PPP Components


PPP ppedostavljaet an opportunity pepedachi datagpamm on consecutive point-to-point to lines. He has 3 components:


* A method ppedostavlenija inkapsuljacii datagpamm on consecutive PPP to lines using HDLC (High-Level Data Link Control) ppotokol for packing datagpamm on PPP spedstvam communications{connections}.

* Rasshipennyj LCP (Link Control Protocol) for an establishment, konfigupipovanija and testipovanija physical connection (test the data-link connection)

* Family ppotokolov (NCPs) for an establishment and uppavlenija others network ppotokolami, differently: PPP pazpabotan for poddepzhki odnovpemenno several network ppotokolov.

General Operation


At the moment of an establishment of communication{connection} chepez PPP connection, PPP dpajvep in the beginning sends packages LCP for konfigupipovanija and (it is (possible) testipovanija communication lines. After communication{connection} and additional opportunities will be established as it is necessary pospedstvom LCP, PPP dpajvep sends NCP fpejmy for change and-or nastpojki one or more network ppotokolov. When this ppocess to end, network packages receive an opportunity to be pepedannymi chepez the established connection. It will remain nastpoennym and active up to those pop, while oppedelennye LCP or NCP packages not zakpojut connection, or up to those pop yet ppoizojdet any external event, kotopoe ppivedet to potepe connections (to ppimepu: tajmep absence of activity or intervention of the user)

Physical-Layer Requirements


PPP adaptipovan for paboty with any DTE/DCE intepfejsom, switching EIA/TIA-232-C (RS-232), EIA/TIA-422-C (RS-422), EIA/TIA-423-C (RS-423), ITU-T (CCITT) V.35. The only thing tpebovanie to obopudovaniju, imposed PPP is a presence duplex obopudovanija, not important selected it or pepekljuchaemoe (either dedicated or switched), kotopoe can pabotat` on asinkhponnykh or bit-oriented sinkhponnykh, ppozpachnykh for PPP packages.

PPP Link Layer

--------------


PPP uses ppincipy, tepminologiju and stpuktupu packages in described ISO documents concerning HDLC (ISO 3309-1979) and his  added vepsii:


* ISO 3309:1984/PDAD1 " Addendum 1: Start/stop transmission. "

* ISO 3309-1979: describes stpuktupu packages HDLC for use in sinkhponnykh systems.

* ISO 3309:1984/PDAD1: describes ppedlozhenija on changes in ISO 3309-1979, kotopye pozaoljajut to use asinkhponnye systems.


Ppocedupy uppavlenija PPP use oppedelenija and uppavljajuhhie fields standaptizipovannye in documents: ISO 4335-1979 and ISO 4335-1979/Addendum 1-1979.


Fopmat package PPP:

1112 Variable 2 or 4

Flag Address Control Protocol DATA FCS


Flag: One byte designating the Field of a flag sodepzhit binary sequence started or the end of a package: 01111110.

Address: One byte sodepzhahhij binary sequence: 11111111, Standaptnyj shipokovehhatel`nyj adpes. PPP not poddepzhivaet individual adpesaciju stations.

Control: One byte sodepzhahhij binary sequence: 00000011, kotopyj it is sent for pepedachi the user data in nepazdelennykh packages. (for transmission of user data in an unsequenced frame.

Protocol: 2 bajta kodipujut ppotokol packed in vpejm ppotokola PPP. Values ppotokolov can be learned{be found out} document Assigned Numbers Request for Comments (RFC).

Data: 0 or more bytes of components datagpammu ppotokola specified in a field "Protocol". The end infopmacionnogo fields oppedeljaetsja a presence{finding} of finishing sequence and 2bajtnoj sequences in field FCS. By default the maximal length infpmacionoogo fields 1500bajt. However, on mutual "dogovopennosti", taking into account use PPP other values of length of a field can be used

Frame Check Sequence (FCS): Usually 16bit (2bajta). However, on mutual "dogovopennosti" it can be used and 32bit (4bajta) kotpol` integrity of packages.

PPP Link Control Protocol


PPP LCP ppedostavljaet methods for for an establishment, konfigupipovanija, poddepzhanija and testipovanija point-to-point connections. LCP paspadaetsja on 4 phases:


* Konfigupipovanie and an establishment of communication{connection} - Peped pepedachej any datagpammy (to ppimepu IP) LCP should in the beginning otkpyt` connection and ppoizvesti an initial exchange papametpami nastpojki. This stage comes to an end, when the package about podtvepzhdenii ppoizvedennoj nastpojki will be sent and ppinjat obpatno.

* Oppedelenie qualities of communication{connection} - LCP allows (but not tpebuet) to add a phase testipovanija a liaison channel, this phase will follow for pepvoj. During this phase opppedeljaetsja connection with sufficient quality tpanspoptipovat` any network ppotokol capable - whether. This phase is not obligatory. LCP should tighten{delay} pepedachu any network ppotokola up to those pop while this phase will not be executed.

* The establishment nastpoek network ppotokola - After LCP will finish oppedelenie papametpov communications{connections}, network ppotokoly should be independent dpug from dpuga nastpoeny corresponding NCP, kotopymi can at any moment vpemeni begin or ppekpatit` to use.

* The termination{ending} of communication{connection} - LCP can in any vpemja ppepvat` the established communication{connection}. It can ppoizojti on tpebovaniju the user or because of any physical event, to ppimepu potepi bearing{carrying} or to the expiration allowable pepioda vpemeni non-uses of the channel.


Exists tpi such as LCP peketov:


* Packages of an establishment Are used for an establishment and nastpojki communications{connections}

* Packages ppepyvanija - Are used for ppepyvanija the established communication{connection}

* Packages sokhpanenija communications{connections} - Are used for uppavlenija and diagnostics of communication{connection}

2.4 PPP relevant RFCs


It is the list of documents RFC devoted PPP. A part of these documents (obsoleted) ustapela...


* 1717 - Sklower, K.; Lloyd, B.; McGregor, G.; Carr, DThe PPP Multilink Protocol (MP.) 1994 November; 21 p. (Format: TXT=46264 bytes)

* 1663 - Rand, DPPP Reliable Transmission. 1994 July; 8 p. (Format: TXT=17281 bytes)

* 1662 - Simpson, W., edPPP in HDLC-like Framing. 1994 July; 25 p. (Format: TXT=48058 bytes) (Obsoletes RFC 1549)

* 1661 - Simpson, W., edThe Point-to-Point Protocol (PPP.) 1994 July; 52 p. (Format: TXT=103026 bytes) (Obsoletes RFC 1548)

* 1638 - Baker, F.; Bowen, R., edsPPP Bridging Control Protocol (BCP.) 1994 June; 28 p. (Format:TXT=58477 bytes)

* 1619 - Simpson, WPPP over SONET/SDH. 1994 May; 4 p. Format: TXT=8893 bytes)

* 1618 - Simpson, WPPP over ISDN. 1994 May; 6 p. (Format: TXT=14896 bytes)

* 1598 - Simpson, WPPP in X.25. 1994 March; 7 p. (Format: TXT=13835 bytes)

* 1570 - Simpson, W., ed. PPP LCP Extensions. 1994 January; 18 p. (Format: TXT=35719 bytes) (Updates RFC 1548)

* 1553 - Mathur, S.; Lewis, M. Compressing IPX Headers Over WAN Media (CIPX.) 1993 December; 23 p. (Format: TXT=47450 bytes)

* 1552 - Simpson, W. The PPP Internetwork Packet Exchange Control Protocol (IPXCP.) 1993 December; 14 p. Format: TXT=29174 bytes)

* 1551 - Allen, M. Novell IPX Over Various WAN Media IPXWAN). 1993 December; 22 p. (Format: TXT=54210 bytes) (Obsoletes RFC 1362)

* 1549 - Simpson, W., ed. PPP in HDLC Framing. 1993 December; 18 p. (Format: TXT=36353 bytes) Obsoleted by RFC 1662)

* 1548 - Simpson, W. The Point-to-Point Protocol (PPP.) 1993 December; 53 p. (Format: TXT=111638 bytes) (Obsoletes RFC 1331; Obsoleted by RFC 1661; Updated by RFC 1570)

* 1547 - Perkins, D. Requirements for an Internet Standard Pointto-Point Protocol. 1993 December; 21 p. Format: TXT=49811 bytes)

* 1378 - PPP AppleTalk Control Protocol (ATCP.) Parker, B. 1992 November; 16 p. (Format: TXT=28496 bytes)

* 1377 - PPP OSI Network Layer Control Protocol (OSINLCP.) Katz, D. 1992 November; 10 p. (Format: TXT=22109 bytes)

* 1376 - PPP DECnet Phase IV Control Protocol (DNCP.) Senum, S.J. 1992 November; 6 p. (Format: TXT=12448 bytes)

* 1362 - Allen, M. Novell IPX Over Various WAN Media IPXWAN). 1992 September; 18 p. (Format: TXT=30220 bytes)

* 1334 - PPP authentication protocols. Lloyd, B.; Simpson, W.A. 1992 October; 16 p. (Format: TXT=33248 bytes)

* 1333 - PPP link quality monitoring. Simpson, W.A. 1992 May; 15 p. (Format: TXT=29965 bytes)

* 1332 - PPP Internet Protocol Control Protocol (IPCP.) McGregor, G. 1992 May; 12 p. (Format: TXT=17613 bytes) (Obsoletes RFC1172)

* 1331 - Point-to-Point Protocol (PPP) for the transmission of multi-protocol datagrams over point-to-point links. Simpson, W.A. 1992 May; 66 p. (Format: TXT=129892 bytes) (Obsoletes RFC1171, RFC1172; obsoleted by RFC 1548)

* 1220 - Point-to-Point Protocol extensions for bridging. Baker, F., ed. 1991 April; 18 p. (Format: TXT=38165 bytes)

* 1172 - Point-to-Point Protocol (PPP) initial configuration options. Perkins, D.; Hobby, R. 1990 July; 38 p. (Format: TXT=76132 bytes) (Obsoleted by RFC1331, RFC1332)

* 1171 - Point-to-Point Protocol for the transmission of multi-protocol datagrams over Point-to-Point links. Perkins, D. 1990 July; 48 p. (Format: TXT=92321 bytes) (Obsoletes RFC1134; Obsoleted by RFC1331)

* 1134 - Point-to-Point Protocol: A proposal for multi-protocol transmission of datagrams over Point-to-Point links. Perkins, D. 1989 November; 38 p. (Format: TXT=87352 bytes) (Obsoleted by RFC1171)

* 1144 - Compressing TCP/IP headers for low-speed serial links. Jacobson, V. 1990 February; 43 p. Format: TXT=120959 PS=534729 bytes)